Getting to know your garden's enemy: annual and perennial weeds
The definition of a weed is any plant growing where it is not wanted. However, there is a very large classification of plants which are weeds and if not controlled will take over a garden. If you look at the root systems of these plants they are usually massive for the size of the plant. It is a taproot, or a rhizome type root, which runs underground and sends up new shoots. While it may not be your favorite gardening task, attacking weeds in the spring is a good time to do severe or deadly damage to them. The perennial weeds pull out easiest in the spring when the ground has recently thawed and is damp. Weeds will also pull easier shortly after a good soaking rain.
Just as there are annual and perennial flowers and plants there are also annual and perennial weeds. The annual weeds can also be classified as cool-season weeds and warm-season weeds. Annual weeds are spread by seeds which are carried into the garden by wind, birds, four-legged animals and you. They can also lie dormant in the soil for years and when the soil is cultivated these seed are brought to the surface, exposed to sunlight and begin to germinate. The deeper the cultivation, the more weed seeds that brought closer to the surface, and have an opportunity to germinate. While a nicely tilled garden is beautiful to behold, keeping tillage to a to a minimum and using organic mulch (grass, straw) is a better way of controlling weeds. Mulches smother weed seeds, while cooling the soil and
Cool-season annual weeds may sprout anytime from fall through spring. They flower in late spring and early summer and then may disappear when the weather warms up in summer. In fall they, as well as all the new seeds from spring, will be back and beginning to germinate.
Warm-season annual weeds start growing in spring, but continue to stay around all summer. The best way to get rid of them is to make sure they do not go to seed. Annual weeds, in contrast to perennial weeds, have a smaller root system and are easier to pull or hoe out. If they go to seed, cutting off the seed help will help control them, but weeding is still an ongoing task.
Some examples of annual weeds are: chickweed, crab grass, lambs-quarters, mallow, pigweed, purple dead nettle, groundsel, nettle, purslane, speedwell, spurge and yellow oxalis.
Perennial weeds are the most difficult to control because they spread by seed and/or a creeping root system. If the entire roots system is not removed any little piece that remains in the soil will re-sprout and continue that weed. This is especially true of taproots, rhizome roots, and the massive roots like the annual weed, chickweed, which break off easily when pulled leaving the root system, or pieces of the root system. If they are tilled, the broken pieces of the root systems just start growing new plants. Because they are so difficult to control or eradicate, sometimes herbicides are the only solution for these weeds. If you pull them and only get part of the root, you know you are losing the battle.
The good thing about attacking perennial weeds in the spring is that they are small, and the plants you want to protect are also small. If you are going to spray glyphosate (Round-up) it is easy to cover up your perennials plants to protect them from the spray because they are still small. However, this window of opportunity is short, so now is the time to take advantage of this.
Some examples of perennial weeds are: bindweed, burdock, dandelion, dock, creeping Charlie, horsetail, knotweed, plantain, poison ivy, quackgrass, thistle and ragweed.
Also as you bring plants home from nurseries and garden centers this spring, make sure there are no hitchhiker weeds in the containers. While plants are potted in good sterile soil, weed seeds are always floating and moving around, and the longer a plant sits in a container at a nursery or garden center, the greater chance it has for a weed seed to land and germinate. So when planting out your purchases, make sure you are not planting another weed.
Kyle Schulz is a Wadena County Master Gardener from Sebeka, and the regular gardening columnist for the Wadena Pioneer Journal.